In recent years, the greenhouse effect of carbon dioxide has been pointed out as one of the causes of the global warming phenomenon, and, across the world, there is an urgent need to take countermeasures for the protection of the global environment.
Conventionally, a method in which a combustion exhaust gas from a boiler, for example, is contacted with an amine-based carbon dioxide absorbing liquid, thereby removing and recovering carbon dioxide from the combustion exhaust gas, has been commonly implemented.
In such a case, conventionally, carbon dioxide has been separated by carbon dioxide absorption and regeneration (carbon dioxide desorption) by a chemical absorption method using an absorbing liquid such as monoethanolamine (MEA) or a sterically hindered amine, for example.
As a process of removing and recovering carbon dioxide from a combustion exhaust gas using an amine-based carbon dioxide absorbing liquid as above, Patent Document 1 below discloses a method in which a combustion exhaust gas is contacted with a carbon dioxide absorbing liquid in an absorption tower, and the absorbing liquid that has absorbed carbon dioxide is heated in a regeneration tower, whereby carbon dioxide is released and, at the same time, the absorbing liquid is regenerated, recirculated through the absorption tower, and reused.